Improvement in the manufacture of steel for boiler-plates



UNITED STATES PATENT OFFIon.

OGDEN BOLTON, J OF OHARTIERS TOWNSHIP, AND JOHN PEDDER, or

' r IITTSBURG, PENNSYLVANIA.

IMPROVEMENT IN THE MANUFACTURE OF'STEEL FOR BOILER-PLATES, &c.

Specification forming part of Letters PateiitNo. 40,673, dated July 8,1873; application filed April 12, 1873.

To all whom it may concern:

Be itknown that we, OGDEN BOLTON, Jr., of Ohartierstownship,andJOHNPEDDER, ofPittsburg, in the county of Allegheny and State'ofPennsylvania, have invented a new and useful Improvement in theManufacture of Boiler- Plate Steel and we do hereby declare thefollowing to be a full, clear, and exact description thereof.

Our invention consists in the manufacture of homogeneous boiler-platesteel, of a uniformly low quality, by subjecting a hard or high steelplate or ingot to the process of decarbonization, by the use of suitableknown decarbonizing agents, at less than a melting temperatiire.

To enable others skilled in the art to make use of our improvement, wewill proceed to describe its manner of operation and use.

i In the manufacture of homogeneous boilerplate steel it has been foundthat however carefully the work is carried on all the plates will not beof uniform quality, andvhence the harder plates have to be thrown out,with a consequent loss or, if, as is commonly the case, they are workedin the danger of disaster from explosion or excessive pressure isthereby materially increased. By our process any such plates, which arefound to be too hard, are readily decarbonized till they are brought tothe desired standard, and then they are worked in without loss ordanger. Also, it is well'known that in making such boiler-plates ofsteel on a large scale the pouring of soft steel such as is required, isattended, with considerable risk of waste and loss. If the steel be madea little harder such risk is largely obviated, but the steel is then toohard for boiler-plate. By our process we,

make the boiler-plate hard, and then decarbonize it to such degree thatit'shall be equal to-the best boiler-plate made, and of the same uniformquality; and such decarbonizing process we perform on the ingotsthemselves, or on the worked steel at any desired subsequent stage inits manufacture. The steel to be decarbonized is inclosed in a suitablebox, case, retort, or furnace, and is covered on all sides, either inseparate blocks or sheets, or in alternate layers, with any knownsuitable oxidizing agents or substances capable of evolving, whenheated, oxygen, chlorine, or fluorine, or other gases which will combinewith the carbon of the steel; or such gases may be generated in aseparate retort and conveyed directly to, and brought into close contactwith, the steel to be decarbonized. While subjected to this process thesteel is to be heated to any desired temperature, but preferably toabout a cherry-red heat. The 'process is carried on in about the manneradopted in the cementation process, and for about the same length oftime, varying with the thickness of the plate, the amouni of thereduction desired, the temperature employed, &c., the effect of whichconditions, as

efiecting the result, are within the knowledge of the skilled workman,and need not be stated The utility of the process is alsov in detail.obvious- The plates, when brought to a uniformly low quality, areremoved and worked up in the usual way.

The conditions under which the ophration above described can besuccessfully carried on will vary considerably, as in other kindredoperations, but for the general purposes we believe the following to bebest: 1 We employ steel containing; from to .4 (three-tenths tofour-tenths) pergcent. of carbon, as this is the" easiest to run forourpurpose, and bring the same to ingot or plate form to a thickness ofabout one inch. Such plates, when embedded in or surrounded by metallicor other suitable oxide, in any suitable known heating-furnace such, forexample, as is used in-the cementation process-is kept at about acherrywred heat for from one and a half to two days, by which they willbe brought to the condition desired. With every increase of, say, .1(onetenth) per cent. of carbon in the steel the decarbonizing operationshould be continued about or a little more than half a day longer.

The plates produced by the process above set forth will come under theheadot homogeneous boiler-plate steel, though theprocess may be arrestedbefore the same degree of decarbonization is carried to the center asexits at the surface. For practical purposes it will be homogeneous, andsuch plates are so recognized in the art. 7

Whatwe claim as our inventlon to secure by Letters Patent, is-

- The manufacture of homogeneous boiler- In testimony whereof we, thesaid OGDEN BOLTON, J r., of Ghartiers township, and JOHN ,and desirePEDDER, have hereunto set our hands.

' OGDEN BOLTON, JR.

JOHN PEDDER.

plate steel-by bringing a hard or high steel to a uniformly low grade,through the agency of deca-rbonizing agents brought to bear on the sameafter pouring, and while in an unmelted state, substantially in themanner Witnesses: v or A. S NICHOLSON, G. H. CHRISTY.

set forth.

